Doubt it. Platnium has extra buildings and maps. There is no real difference to gameplay from my understanding ....but 2011 is the base game, then they released 2012 which added new structures, new maps, a starter guide, opens the game to modding and allows you to share your mods. (wikipedia Cities_XL)

Platinum was basically an expansion pack for Cities XL 2012 which adds 50 new buildings and new maps. Of course Platinum is now available as a full version stand alone edition.

It is a single core game - no matter what you do, no matter how beefy you make your hardware, Cities will always run on a single core. Some people report it actually plays better on older machines than newer ones. Yes, it slows when the cities get really big. For some its unbearable, but I can play for hours and hours at a time without needing to restart it.

It's a coding problem and generally cant be fixed with a patch (and Focus wont make the source code available) .... the game needs a complete rewrite, which just aint gonna happen. Thankfully it has a huge fan community.

Different things can cause lag, so they can have different fixes. One seems to be a memory clog or unable to dump cache - every time you delete an object, it remains in the memory until you restart the game. Another might be too much traffic and pedestrians as the city grows larger. There are a couple of "fixes" to help with memory, but none solve the issue entirely.

Overall Platinum should be more stable than 2011, because bug fixes were included with the 2012 update. Some ppl say the original 2009 version runs the best tho.